Lotus Elan

I have Konis! Now, a few questions.

PostPost by: jbeach » Wed Aug 09, 2017 7:55 pm

Dear Elan Suspension Experts,

Upon removing my rear suspension for rebuild, I assumed my dampers were original and must, therefore, be replaced. I'll have to say, when I checked their function, their operation was oh-so-smooth and seemed to have perfect damping action. So I was hopeful . . . but needed to take them out to be certain, as the previous owner never mentioned replacing them.

After more trouble than I'd like to admit, today I finally removed my rear shock inserts from their tubes. To my utter delight, some previous owner had replaced my original dampers with these Konis!
beach-koni-1.jpg and

beach-koni-2.jpg and

So I have a few questions:

1. What does "Heavy - Turn" embossed on the shock tube in the first photo mean? I know I need to read the entire message, but I just removed it during lunch and needed to return to my desk (where I am now avoiding my legal practice by typing this). Is this part of the Koni instructions on how to adjust the damping action?

2. As you can see, in drilling out the "punch" on my tube, I ham-handedly managed to drill the hole into the shock itself. Have I compromised the damper? Do I need to put a bead of weld in to plug the hole? or does the functional part of the damper end below the threaded area I drilled through?

3. Can anyone provide any information on this particular model Koni? When it was made, whether it is adjustable, is it rebuildable, etc.?

If these shocks are functioning properly, I see no reason to replace or rebuild them. Thoughts?

As always, thank you in advance for your attention and expertise.

-John
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PostPost by: 2cams70 » Thu Aug 10, 2017 12:14 am

These are early version Koni strut inserts that have the gland nut integral with the outer tube unlike later Koni inserts that have the gland nut separate. They would be 70's vintage I'd say. To adjust them push the piston rod right down. In this position rotate the rod slowly whilst still gently pushing down. You should feel a point where the rod drops down a fraction and engages with the adjustment foot valve. Whilst in this position keep turning the piston rod anticlockwise until it stops. This is the softest (OEM) setting. It's also worthwhile counting and noting the number of turns to reach this position as this will give a reference point as to where the previous owner set the dampers. Turning the piston anticlockwise softens the rebound damping. Clockwise hardens the rebound damping - hence the direction arrow stamped on the outer tube.

I wouldn't worry too much about the small hole you have accidentally drilled. It doesn't appear to have gone all the way through in any case. Just make sure the threads are cleaned up to remove any burrs. If it has gone all the way through and is leaking oil I'd tap it out the smallest amount possible and fit a grub screw sealed with Loctite to block it up. Make sure the head of the grub screw sits below the level where it would interfere with the gland nut thread engagement. I wouldn't risk welding.

These shocks are rebuildable (subject to parts availability as they are early types). Check to see that they aren't leaking oil - move around in all positions (lay on side, upside down, etc.). Check to see that the piston rod is not sloppy in the upper bush. Check to see that the piston rod is straight and the chrome plating is in good condition with no corrosion. Check to see that the damping action is smooth in bump and rebound. If the insert has been laying on it's side it may take a few strokes to remove oil air bubbles to properly assess.

If it passes these tests and has no other sign of physical damage I would be inclined to leave well alone. You may need to play around with the adjustment a bit to find a setting to suit your tastes. I generally find a setting that is 1 to 1.5 turns away from the softest works best for general usage on most cars with standard springs - but I haven't tried this on a Lotus.
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PostPost by: elj221c » Thu Aug 10, 2017 11:18 am

You might find this useful.

img001.jpg and
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PostPost by: jbeach » Thu Aug 10, 2017 7:10 pm

Now THIS is what is so amazing about the lotuselan.net online community! I post a question about an obscure 40-year-old Koni insert and within about 12 hours receive two knowledgeable responses from across the globe. Amazing - thank you both!!

The 70s vintage of this Koni damper sounds about right. I purchased this car from an owner who had purchased it from another person about 25 years/25,000 miles earlier. The gentleman I purchased from said he did not do any work like this. But the previous (and I think first) owner had had the engine built by Dave Bean. He obviously upgraded to these Koni dampers during the 70s or 80s.

This Elan has about 42,000 miles showing and I believe that's close to correct. Every part I've taken off or looked into has very little wear. That includes these Koni inserts, which have straight, shiny, uncorroded piston rods and seals that appear solid and uncompromised. They have solid damping action from full compression to full extension.

The only reason I may replace these is I'm installing CV drive shafts and am considering Koni inserts with slightly shorter piston rods to limit droop. I'll be making that decision shortly, but it's very good to know I could stick with these inserts and expect them to measure up to the "fast road" suspension specification I'm going for. (But, seriously, aren't all Elans fast road? 8) )

Anyway, thanks again for taking the time to share your knowledge.

Best regards,

-John
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PostPost by: elj221c » Fri Aug 11, 2017 10:28 am

John,

I'm not sure that just shortening the rods will work in a satisfactory manner. Surely if you reduce their length the adjusting mechanism will be short of the valve adjuster?

I had my new (mine 86R 1371) Konis shortened to fit shorter (26R length?) strut tubes. FYI, from my notes of 1984, the length of the tube above the hub carrier casting is 9.5". So, yes, the rods are shorter but also so are the outers so that they can still be adjusted. They were also revalved to suit my 120lb 2.5" springs.

Total cost of the struts and modification from Banks, Peterborough, was ?135!!
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PostPost by: nmauduit » Sun Aug 13, 2017 10:19 am

jbeach wrote:The only reason I may replace these is I'm installing CV drive shafts and am considering Koni inserts with slightly shorter piston rods to limit droop. I'll be making that decision shortly, but it's very good to know I could stick with these inserts and expect them to measure up to the "fast road" suspension specification I'm going for. (But, seriously, aren't all Elans fast road? 8) )
-John

2 other options to limit travel without cutting the rods would be
1) add a tie to stop droop at a preset length (I'm presently doing that on my car with a loop of 3mm stainless cable)
2) open the shocks and insert an adequately machined stop inside (I'm planning to try that next, a less than 2" long nylon/rilsan drilled rod should do for my application)
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PostPost by: reb53 » Mon Aug 14, 2017 6:53 am

When I fitted my Koni inserts about 30 years ago I seem to remember that the instructions were quite clear as to why you would alter them.
It was to compensate for wear, not to try and out-think Colin Chapman when it came to matters of damping and suspension behaviour.
I've put a lot of miles on them since and have yet to feel they need changing.

When fitting, their precision was certainly most impressive, the rods slowly sinking under their own weight, whereas the Armstrongs needed a hefty push, even when new.
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PostPost by: 2cams70 » Tue Aug 15, 2017 4:22 am

You'd be doing yourself an injustice not to experiment with the settings a bit. Don't just fit and forget on the softest setting. Adjust them in pairs initially half a turn each until you find a setting that best suits your taste. Note that the adjustment only alters the rebound damping. Bump damping is preset and cannot be altered without a change of valves. I haven't yet fitted a set where the "out of the box" soft setting was ideal.

I've never had problems with Konis going soft with use and requiring readjustment to compensate. They are very long lived. Oil leakage is normally the only problem that occurs with them.
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